The present invention relates to a detector arrangement and more particularly to a detector arrangement that is adjustable for inclusion in a preventive protective system for a process plant.
The detector arrangement according to the invention comprises at least two sensor units, with a unit for evaluating the output signal of each sensor unit and an activating unit capable of co-operating with the evaluating units.
The activating unit is designed so that, dependent on the output signals from the evaluating units, preferably via a calculation circuit, it can be caused to pass from a first position to a second position, where the second position may be intended more or less to activate one or more means for preventing damage.
The phrase xe2x80x9cmore or less to activatexe2x80x9d said activating unit means to control said means towards a degree of activation corresponding to an assumed requirement.
Various embodiments of detector arrangements of the type described in the introduction are already known.
Reference is made to the content of U.S. Pat. No. 5,749,420 as an example of the background art.
Considering the features associated with the present invention, the content of U.S. Pat. No. 5,740,867 may also be mentioned as previously known.
Technical Problem
Considering the circumstance that the technical deliberations one skilled in the relevant technical art must perform in order to offer a solution to one or more technical problems posed, are initially an insight into the courses of action and/or the sequence of courses of action to be taken and also a choice of the means required, and on the basis thereof, the following technical problems should be relevant in arriving at the present inventive concept.
Taking into consideration the previous state of the art as described above, it must be deemed a technical problem to be able to create such conditions in a preventive protective system for a process plant that, one the one hand, the number of influences on the activating unit that would not have entailed some risk of fire or other damage is reduced and, on the other hand, not to refrain from an influence on the activating unit on such occasions that would have resulted in damage.
It is thus also a technical problem, at every effort and course of action undertaken with the object of reducing the number of influences, to create conditions for a reliable evaluation of the relevant criteria that affects the risk of fire or other damage.
It is thus also a technical problem to be able to perceive the significance of and the advantages associated with, with great accuracy, not only having the thermal energy of a particle or the combined thermal energy of a number of particles and/or the glow or flame of a particle evaluated, but also hsving the tendency of a material flow to initiate fire or other damage due to the presence of an evaluated particle, determined.
A technical problem is entailed in co-ordinating information as to current energy content and information as to the tendency for damage occurring, so that the activating unit is influenced with greater accuracy than previously.
A technical problem is entailed in improving the effect of and the total result obtained from sensor units and detector arrangements with associated calculation circuits utilised so that a safety margin between energy content of a particle and the tendency of a material flow to initiate fire or other damage due to the presence of this particle, can be controlled and kept small without a deficiency occurring in the ability of the activating unit to be influenced when the energy content in a sensed particle in a known environment created in the media flow will be able to cause damage.
A technical problem is entailed in being able to perceive the significance of and advantages associated with not only evaluating the energy content of an individual particle (or the total or calculated energy content of a plurality of densely oriented particles), but also observing the momentary tendency of the material flow, as a result of the presence of this particle, to cause fire or other damage in a conveyor and/or a silo or the like.
A technical problem is entailed in being able to perceive the significance of not just refining the design of one or more of a first category of sensor units that are designed, via their circuits for evaluating an output signal, to be able to determine the energy content of a particle present with great accuracy, but also to perceive the significance of utilising one or more sensor units of a second category designed, via their circuits for evaluating an output signal, to be able to determine the tendency of the particle surroundings to fire or other damage.
A technical problem is entailed in being able to perceive the significance of and advantages associated with allowing an activating unit to be designed to pass from a first position (rest position) to a second position (active position) only when a momentary combined energy content and the determined tendency to fire or other damage, to indicate a risk of fire or other damage, and where a calculated risk may then lie extremely close to, but still below the actual risk or the risk value for fire or other damage.
A technical problem is thus entailed in, on the basis of information received relating to the energy content of a particle and the tendency of the surrounding environment to combustion or other damage, being able to perform an adequate calculation of the probability and/or possibility of damage.
A technical problem is entailed in being able to perceive the significance of and advantages associated with allowing an activating unit to be designed still to assume a first position when a momentary combination of determined energy content and determined tendency to fire or other damage admittedly indicates a risk of fire or other damage, but when a calculated risk value lies very close to, but still below the actual value for fire or other damage, reduced by a risk margin.
A technical problem is also entailed in being able to perceive the significance of utilising one or more units of said first category and one or more sensor units of said second category.
A technical problem is entailed in being able to perceive the significance of and advantages associated with allowing said first category of sensor units for evaluating the energy content of existing particles, to be based on temperature sensing, wave-length analysis and/or the use of one or more second sensor units.
A technical problem is entailed in being able to perceive the significance of and advantages associated with, within said second category of sensor units, allowing one sensor unit to be used where sensing the temperature determines the tendency of the material flow, and thus the particle surroundings, to fire or other damage.
A technical problem is also entailed in being able to perceive the significance of allowing a sensor unit to be used that is especially designed to be able to sense the moisture content in the material flow, and thus in the particle surroundings.
A technical problem is also entailed in being able to perceive the significance of utilising a sensor unit that is designed to be able to determine the fire tendency or other damage of the particle surroundings by means of sensed oxygencontent.
It should no doubt also be deemed a technical problem to be able to perceivethe significance of and advantages associated with allowing a sensor unit to be used that is designed to be able to determine the tendency of the particle surroundings to fire or other damage by means of evaluating the dust concentration.
It should furthermore no doubt be deemed a technical problem to allow a sensor unit to be used that is designed to be able to determine the tendency to fire or other damage of the particle surroundings by means of evaluating the particle size.
It should furthermore no doubt be deemed a technical problem to provide a sensor unit that is designed to be able to determine the tendency to fire or other damage of the particle surroundings by means of evaluated turbulence intensity in the material flow within a pipe section.
It is also a technical problem to be able to perceive the significance of and advantages associated with allowing said sensor unit to be designed to be able to determine the tendency to fire or other damage of the particle surroundings, or alternatively the ignition energy required, by means of evaluating the ignition temperature.
A technical problem is also entailed in being able to perceive the significance of and advantages associated with allowing one or more of the sensor units mentioned above, to be used in order to be able to determine the tendency of the particle surroundings to fire or other damage on the basis of various criteria.
A technical problem is also entailed in being able to perceive the significance of and advantages associated with allowing the unit evaluating the output signal of each sensor unit to emit its own value, one representing the energy content, one representing the fire tendency or tendency to other damage of the particle surroundings, and allowing a list or algorithm included in the calculation circuit to determine if and how the activation circuit shall be influenced and which extinguishing arrangement(s), amongst a plurality of alternative means available, shall be activated or, by means of calculations, evaluate what action shall be taken.
It should similarly be deemed a technical problem, on the basis of criteria stipulated, to select the second, active, position depending on the energy content and/or thermal content, and to determine the tendency to fire or other damage in order to be able to evaluate and select one or more of a plurality of available courses of action.
Solutions
To enable solution of one or more of the technical problems described above, the present invention takes as its point of departure a detector arrangement adjustable for inclusion in a preventive protective system for a process plant comprising at least two different categories of sensor units, a unit for evaluating the output signal of each sensor unit and a calculation circuit and activating unit capable of co-operating with the evaluating units, said activating unit being capable, dependent on the output signals from the evaluating units, of being caused to pass from a first position to a second position
The present invention shows particularly that one or more sensor units included in a first category of sensor units shall be designed, via its circuit for evaluating output signals, to be able to determine the energy content of a particle present, that one or more sensor units included in a second category of sensor units shall be designed, via its circuit for evaluating output signals, to be able to determine the tendency of the particle surroundings to fire or some other damage.
It is also stated that the activating unit shall be designed to pass from a first position to a second position only when the combined energy content and the tendency determined indicate risk of fire or other damage.
Proposed embodiments falling within the scope of the inventive concept show that among the sensor units falling within said first category one sensor unit shall be designed to determine the energy content of a particle occurring by means of temperature sensing and/or wave-length analysis.
It is also stated that among the sensor units falling within said second category of sensor units one may be designed to determine the tendency of the particle surroundings to fire or other damage by means of temperature sensing.
The second category of sensor units may also include a sensor unit designed to be able to offer moisture content sensing, a sensor unit for sensing oxygen content, a sensor unit for sensing dust concentration, a sensor unit for sensing particle size of the transported material, a sensor unit for sensing turbulence intensity, in order therefrom to determine an ignition temperature or, alternatively, the ignition energy required.
The invention also shows that the unit evaluating the output signal of each sensor unit shall emit its own value, one representing the energy content, one representing the fire tendency or tendency to other damage of the particle surroundings, and that a list or algorithm included in a calculation unit will determine if, and in that case, how the activation circuit shall be affected.
Advantages
The foremost advantages that may be considered characterizing for a detector arrangement in accordance with the present invention are that conditions are provided, with the aid of a first category of sensor units, that enable evaluation of the energy content in a particle occurring in a preventive protective system for a process plant, and also the use of a second category of sensor units that are designed, via a circuit evaluating their output signals, to be able to determine the tendency of the particle surroundings to fire or other damage, and that both these criteria in combination shall indicate momentary risk of fire or other damage, and when a calculated probability and/or possibility of damage exceeds a predetermined value, the activating unit is activated to pass from a first position to a second position and thereby selectively activate one or more devices or means pertaining to the process plant in order thereby to extinguish fire or prevent other damage.
The principal characteristic features for a detector arrangement showing the significant features of the present invention are defined in the characterizing part of the appended claim 1.